Lathe center



Patented Mar. 26, 1946 LATHE CENTER Frederick N. Reynolds, Augusta, Ky.

Application April 10, 1944, Serial No. 530,281

4 claims. "(01. :s2- 33) The present invention relates to improvements in centering devices for lathes and is particularly directed to a center having a single seat formed therein which positively maintains a Work engaging member at its dead center position and.

precludes radial displacement of said member in the seat.

An object of the invention is to provide a center of simplied construction having-awork engaging member which under axial work clamping action of the lathe automatically centers itself relative to its supporting shank and the Work, and which precludes all radial displacement between said member and the shank.

Another object of the invention is to provide a single ball center which is rotatably positioned in a conically shaped seat member mounted in the center shank, the ball being adapted to engage the seat about a small circle of its spherical surface lying in a plane at rightangles to the axis of said shank.

A further object of the invention is to provide an improved attachment for preventing uneven wear in rotatable lathe centers to thereby insure an eicient and accurate device over a relatively long period of use, and to also provide an economical means for replacing the Wearing part of the device.

Other objects and novel features will be apparent from the following specication and drawing which illustrate preferred embodiments of my invention, and in which:

Fig. 1 is a side elevational veiw of my lathe center, its cooperating tail stock and the work supported thereby being shown in central cross section.

Fig. 2 is an enlarged cross-sectional View taken on line 2--2 of Fig. 1.

Fig. 3 is a central cross-sectional view of a modied form of my center.

Fig. 4 is a central cross-sectional view showing another modication of my center.

My invention includes a tapered shank I which may be fitted in a tapered hole 'l formed in a conventional tall stock 8 of a lathe. This shank is provided with a head portion 9 which has formed therein a conically shaped seat I0 disposed coaxially with the longitudinal axis of the shank. As most clearly shown in Fig. 2, this seat has the shape of a right circular cone and its vertex II lies within the head and on the longitudinal axis of the shank, its lateral surface I2 converging outwardly from said vertex to the outer face ,K I3 of the head, said face being disposed in a'plane at right angles to said shank axis.

A spherical Work engaging member I-4 is positioned in the seat and is in contact with an intermediate portion of its lateral surface about a small circle I5, said circle lying in a plane at ri-ght anglesto the axis of the shank.

When the member is in the above described position a major portion I6 of its surface extends beyond the face I3 of the shank. As shown in Figs. 1 and 2, this portion I6 is adapted to engage an intermedaite portion of a conventional, tapered recess Il formed in the work I8, the spherical member being in contact with the Work about a small circle I9 of its surface which lies in a plane at right angles to the axis of the shank or in a plane parallel to the plane of the small circle I5.

A means for retaining the member I4 in its seat when the tool is not in use comprises a cap 20 having the form of a frustum of a cone. This cap has a peripheral bead 2| in engagement with aliange 22 formed on a collar 23. The collar is removably held on the shank through cooperating threads 24. The outer portion of the cap is provided with a peripheral aperture 25 which freely engages a reduced portion of the spherical member I4 at a point beyond the plane of its center. Y

The seat II) in the shank and the spherical member I4 are of hardened metal and the space between the vertex of the seat and the inner portion of the spherical member is filled with a suitable lubricant. The work I8 is of a relatively soft metal and upon rotation of said Work the ball is adapted to rotate in its seat. During operation my center positively maintains the work on its true rotary axis due to the fact that the spherical member engages the Work around a small circle I9 and engages the conical seat around a small circle I5, both circles being disposed at right angles to the common axis of the shank and the rotary axis of the Work. Under operational work clamping pressure of the lathe the spherical member is confined in the conically shaped seat I0 and the conically shaped recess I1 formed in the Work and due to the action of the opposed lateral surfaces the member I4 maintains the shank and the work in axial alignment. Furthermore, under prolonged usage the rotary spherical member tends to Wear evenly in which event it merely seeks a dead center position in the seat which is removed inwardly from its initial position therein. The composite tool may be renewed by removing the nut and cap, inserting a new spherical member in the seat and replacing the cap and the nut. The spherical member also precludes radial displacement between the work and the shank due to the fact that said member is positioned between two opposed conical recesses formed in the shank and in the work.

My invention includes the device shown in Fig. 3 wherein the shank 26 is provided with a conical recess 21 which is formed in the face 28 of the shank and disposed coaxially therewith. This recess receives the"vertx port'io'xr 29 of? 'ic'onically 10 shapedmember '30 having formedthereinfa conical seat 3| for receiving a spherical work engaging member 32. The member 32 is retained in the seat by means of a cap 33 which is provided at its inner endwith a peripheral shoulder 34- 15 which is engaged by a flange 35 forme'don'fa nut 36. The nut is removablysheldsonr the. shank by means of cooperating threa`ds"3. Thisform of my invention is adapted to provide altoolfor; L' centering various types of work which have coun- 2o ""terisu'nkf recesses et'fdiierrent' 'iliametersL` AThe size 'of the'sphericialx'neinbeijif 2f-held in theshank 2 6 may be 'adjusted-by interchanging:theeV seat 30 -forone of larger or 'smaller' lateral v'area and-in- H' serting thereinan *appropriate*spherical mem- 25 doler.'vv This mo'dicatiorr' W6u1d*"also require the use "of vari'ossized' re'tiner capsrhavingappropriateball receiving, .apertires'formed therein;v s miirigjr isi-shown anotne'rfniodiedfformof A 'my invention 'jwhereinf'ja shank" '13'8 l is "j'provided `'30 with aconical "'se'at '39 Lior'ire`c`eivingia; work en- 'oizvpos'e'd right circular eone's "j'oinedf'along their fcomr'no'nbase. :"Tliis lmemberlris retained j in its What is claimed is:

1. In a lathe center the combination of a shank having a cone shaped hole formed therein, a cone shaped seat member removably positioned in the hole, a spherical member positioned in the seat and having a portion extending therefrom, and a cap removably mounted on the shank and adapted to retain said members in their operative positions on the shank.

22X Inaflatlie `center the combination of a shank, 'fa"oylindrical head on-theishankfacone shaped recess formed in the head and disposed coaxially @with the shank, a hollow cone Shaped seat memzberx removably positioned in the recess and havin'g'a tapered end extending beyond said recess, r`a-sphericalmember removably positioned in the .v seat membena cap engaging the tapered end of theseat'memberand the spherical member, and

agca'pretaining nut threaded to the head.

3. In a lathe center the combination of a shank; arecess formed inthe shank-en'd,fa `hollow lcone shaped' seat member in the recess;anjd lhavingan end extending beyond the shanleend, Aaiball positioned inthe seat member, -a seat'mem- '-bera/-ndfball engaging cap, and a cap retaining nut threaded Ato the head.- i "l 4. In a lathe center the combination `Iof a shank, a 4cylindrical head onthe shankfacone "shaped recessformed'in thefheadand disposed "coaxial-ly with the `-shankpafY hollow-cone shaped seat 'memberg removably positioned inthegrecess v-andhaving a' tapered end extending' beyond-said recess' a `spherical member removablypositioned in the seat member, a; cap having; the shapeof a seat'by'a cap 41 which "is removablypsfitionedon" l'irustrum ofV la' cone-and engagingthe tapered the shankby cooperationbfa ange 42 formed "on a ut '43thieaded.tothejshank and a'fperiph *eral ange M* formed:bn'isaid'foapr l *When vthe louter' vksectiorrol' the Ymemlcier; has" 'become worn v`:ric'ler'prolor'rged Contact with the'rotating Awork 40 cooperating with the flange an supported 1 thereby the niember maybe :reversed end Afor "end"and"thfiiiiie1; section 4may then be used as the Work contacting portion.

F endof-'theseat member-at itsintermediateportion' and having Nits reduc'edfiopen end engaging the'spherical memben-a peripheral ange on the I 'enlarged endl of Ithecap; and" cap --retaining nut d threaded to the FREDERICK N.r REYNOLDS. 

